[underscore]

I think the answer kind of depends on the nature of the project.

Re-writing something you have now in another language/framework can be (in addition to fun) a great way to learn the new language/framework. If this is just a fun project, well, cool - best of luck to you. If this is a business, something that you'd like to start making money (or at least getting press) from, then maybe the delay will hurt you more than the fun will help you.

In my case, the website was the online component of a small university department. I inherited a PHP codebase that worked, but that I really didn't like, and opted to re-write it in Python/Django. I'm really happy with the decision: I think it was a great way to learn the framework, and the result is a lot better than the PHP site that it replaced, but I don't think I would have done it if I hadn't had a working PHP site to placate students while I was working on it.

Good luck with whatever route you choose to go.